Messages in this thread | | | From | Joel Fernandes <> | Subject | Re: [PATCH v3] rcu: Add a minimum time for marking boot as completed | Date | Wed, 8 Mar 2023 07:09:42 -0800 |
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> On Mar 8, 2023, at 7:01 AM, Frederic Weisbecker <frederic@kernel.org> wrote: > > On Wed, Mar 08, 2023 at 05:52:50AM -0800, Joel Fernandes wrote: >> Just to add to previous reply: >> >> One thing to consider is that it is more of a performance improvement for >> booting in expedited mode to fallback to normal later, than a bug >> fix. Repeated synchronize_rcu() can easily add 100s of milliseconds and to >> remedy that — a conversion of the call from normal API to the expedited API >> will not help. > > 2 things to consider: > > 1) Is it this about specific calls to synchronize_rcu() that repeat a lot > and thus create such measurable impact? If so the specific callsites should > be considered for a conversion. > > 2) Is it about lots of different calls to synchronize_rcu() that gather a big > noise? Then the solution is different. > > Again without proper analysis, what do we know?
Again, no one disputed that proper analysis is needed. That is obvious. I was just responding to your assumption that if boot is slow, user space will also be slow. That is not a good thing to conclude because there are many factors. Slowness at boot may be considered a bug, but slowness after boot may not be (say if the user care mores for power later).
On my side I am planning to dig deeper into our boot process, but it will take time. I hope Qiuxu can do the boot analysis on his side.
Thanks.
> > Thanks.
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